25-53 Alternation Timer Value
Range: Function:
0* [0 - 7 ] Readout parameter for the alternation time interval
value set in parameter 25-52 Alternation Time
Interval.
25-54 Alternation Predened Time
Range: Function:
Size
related*
[ 0 -
0 ]
If selecting [3] Predened Time in
parameter 25-51 Alternation Event, the variable
speed pump alternation is carried out every
day at the specied time set in alternation
predened time. Default time is midnight
(00:00 or 12:00AM depending on the time
format).
25-55 Alternate if Load < 50%
Option: Function:
NOTICE
Only valid if parameter 25-50 Lead Pump
Alternation is dierent from [0] O.
If selecting [1] Enabled, the pump alternation can
only occur if the capacity is equal to or below
50%. The capacity calculation is the ratio of
running pumps (including the variable speed
pump) to the total number of available pumps
(including variable speed pump, but not those
that are interlocked).
Capacity =
N
RUNNING
N
TOTAL
× 100 %
For the basic cascade controller, all pumps are of
equal size.
[0] Disabled The lead pump alternation takes place at any
pump capacity.
[1] * Enabled The lead pump function is alternated only if the
number of pumps running are providing less
than 50% of total pump capacity.
25-56 Staging Mode at Alternation
Option: Function:
[0] * Slow This parameter is only active if the option selected
in parameter 25-50 Lead Pump Alternation is dierent
from [0] O.
2 types of staging and destaging of pumps are
possible. Slow transfer makes staging and destaging
smooth. Quick transfer makes staging and destaging
as fast as possible; the variable speed pump is cut
out (coasted).
At alternation, the variable speed pump is ramped
up to maximum speed and then ramped down to a
standstill.
25-56 Staging Mode at Alternation
Option: Function:
[1] Quick At alternation, the variable speed pump is ramped
up to maximum speed and then coasted to a
standstill.
Illustration 3.93 and Illustration 3.94 show alternation
in both quick and slow congurations.
Time
Time
Alternation command/PID stops
Mains operation
Destaging freq.
Mains operation
Staging freq.
PID contr.
starts
130BA613.10
5 s
f
MAX
f
MIN.
f
MAX
Illustration 3.93 Slow Conguration
130BA614.10
100ms
Time
Time
Mains operation
Coast
200ms-2s (default 500ns)5 s
Illustration 3.94 Quick Conguration
25-58 Run Next Pump Delay
Range: Function:
0.1 s* [0.1 -
5 s]
This parameter is only active if the option
selected in parameter 25-50 Lead Pump
Alternation is dierent from [0] O.
This parameter sets the time between stopping
the old variable speed pump and starting
another pump as a new variable speed pump.
Refer to parameter 25-56 Staging Mode at
Alternation for description of staging and
alternation.
25-59 Run on Mains Delay
Range: Function:
0.5 s* [ par.
25-58 - 5
s]
This parameter is only active if the option
selected in parameter 25-50 Lead Pump
Alternation is dierent from [0] O.
This parameter sets the time between
stopping the old variable speed pump and
starting this pump as a new xed speed
pump. Refer to Illustration 3.93 for description
of staging and alternation.
Parameter Description Programming Guide
MG20OB02 Danfoss A/S © 05/2018 All rights reserved. 215
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